Method of making composite metal slabs



July 6, 1943. c. A. MEDSKER METHOD OF MAKING COMPOSITE METAL SLAB Filed Oct. 18, 1940 main-II INVENTOR. CHARLES A-MEDSKE F? u .Y. E m m T A atented July 6, 1943 METHOD OF MAKING COMPOSITE METAL SLABS Charles A. Medsker, Cleveland Heights, Ohio, assignor to William/L. Ul mer Application October 18, 1940, Serial No. 361,695

8 Claims.

ing and the following description setting forth in detail one approved method of carrying out the invention, such disclosed method however, constituting but one of the various ways in which the principle of the invention may be used.

In said annexed drawing: v

Fig. 1 illustrates more or less diagrammatically the various steps in one method of making the composite slabs;

Fig. 2 illustrates, in a similar manner, a modification in one of the steps of the method, and

Fig. 3 illustrates, in a similar manner, still another modification in one of the steps of the method.

Referring more particularly to Fig. 1 of the drawing, a mold I, such, for example, as is disclosed in my co-pending application Serial No. 280,593, now Patent 2,253,526, dated August 26, 1941, and having a cold slab 2 of steel or other metal therein, the upper surface of which slab has beeen previously prepared, as by suitable machining and cleaning operations, is placed under a spout 3, through which a liquid flux 4 is poured onto the slab.

The flux is preferably of the type disclosed in the co-pending applications of Jerome M. Bialosky and Menahem Merlub-Sobel, Serial Nos. 329,494 now Patent 2,281,910, dated May 5, 1942, and 335,406, now Patent 2,277,064, dated March 24.. 1942, that is, a liquid flux of the alkyl-borate "we, and after this flux has spread uniformly over the surface of the slab,'it is ignited, with the result that the alcohol in the flux is consumed and a relatively thin residue or deposit of bo-ric oxide is left on the surface of the slab.

The mold containing the boric oxide-coated slab is then placed in a furnace 5, having a slightly reducing atmosphere, and the slab is heated in this furnace to a temperature of from about 800 F. to about 1500 F.

The heater slab is then moved to a position under the pouring spout 1 of a receptacle 6 containing a molten metal other than the metal of the slab 2, such, for example, as copper or an alloy of copper. Thepouring spout is preferably of a width coextensive with the width of the slab.

The temperature of such molten metal is maintained as high as is practicable, such temperature, in the case of copper, being approximately 2250 F. A temperature range of from about 1900 F. to about 2500 F. will take into consideration copper and virtually all of the usual alloys of copper with which it is desirable to coat steel.

The molten metal is preferably poured onto the flux-coated slab as the slab is slowly moved thereunder, in the direction indicated by the arrows in Fig. 1, by means of a conveyor chain or other means, as described in my aforesaid copending application.

As the slab is thus moved along under'the pouring spout 1, the slab is also preferably, but not necessarily, subjected to the action of a burning reducing gas, such as natural gas, supplied by torches 8 and 9, arranged at the front and rear respectively of the pouring spout i, such gas having entrained therein a vaporized flux obtained by passing the gas, before combustion thereof, through a receptacle containing a liquid flux of the character hereinbefore described. In this way flux is applied to thoseportions of the upper surface of the slab which may not have been thoroughly covered in the first application of flux which has been described, and also, a slight puddling action is created, which is effective to thoroughly cleanse the applied copper or other metal by the action of the flux thereon.

The coated slab, before it has cooled to any substantial degree, is then passed through a second furnace l0, having a reducing atmosphere therein, and in this furnace the slab and metal with which it has been coated are brought up to a relatively high temperature, about 2000 F. in the case of copper, and corresponding temperatures for copper alloys, and, in any event, above the melting point of the coating metal.

The composite slab is permitted to soak at this temperature for not less than two minutes, after which it is removed from the furnace and permitted to cool to a rolling temperature, 1. e. about 1600 F., at which temperature it may be removed from the mold, and rolled into plates or sheets, or, if desired, may be permitted to cool to atmospheric temperatures and stored for future rolling.

The reheating or soaking of the slab is effective to complete the formation of the bond between the slab and applied metal, and this bond has been found to be considerably'superior to that formed without the addition of the reheating step.

As a variation or modificationof the aforesaid procedure, the slab, instead of being subjected to fiuxing by pouring a liquid flux thereon and igniting the flux, may be subjected to a fluxing operation, such as is illustrated in Fig. 2. In this modification, the mold I, containing the slab 2, is inverted and moved along over torches ll, similar to the torches 8 and 9, and as a result of the combustion of gas flowing through the torches, having a vaporized flux of the character described entrained therein, a thin film of boric oxide is deposited on the entire surface of the slab, after which the mold is returned to its normal position and moved along to the preheating furnace 5.

Instead of applying the flux to the slab in the manner illustrated in Fig. 2, it may be applied to the inverted slab in the manner shown in Fig. 3, in which the slab is slowly moved along over a pan l2 containing a burning liquid flux l3 of the character which has been described. In this way, a thin film of boric oxide is deposited on the entire surface of the slab, after which the mold is returned .to its normal position and mozed along to the preheating furnace 5.

Instead of pouring molten copper or other metal to be applied to the steel slab, as illustrated in Fig. 1, a solid sheet or slab of such metal may be placed in the mold in direct contact with the flux-coated slab, and the mold moved into the furnace III, as a result of which, the sheet or slab of copper or other applied metal is melted and becomes firmly bonded to the steel.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the method herein disclosed. provided the step or steps stated by any of the following claims or the equivalent of such stated step or steps be emplayed. 7

I therefore particularly claim as my invention:

1. A method of making a composite metal slab which consists in contacting the slab with a burning flux ofthe alkyl-borate type to deposit a thin layer of boric oxide on the surface thereof, heating said flux coated metal slab to a temperature of from about 800 F. to about 1500 F., applying a metal different from said first metal to the flux coated surface of the first layer of metal, heating both metals to a temperature above the melting point of the applied metal to cause a strong bond between the component metals and then cooling thecomposite slab.

2. A method of making a composite metal slab which consists in contacting the slab with a burning flux of the alkyl-borate type to deposite a thin layer of boric oxide on the surface thereof, heating said flux coated metal slab to a temperature of from about 800 F. to about 1500 F., applying copper to the flux coated surface of the first layer of metal heating both metals to a temperature above the melting point of the copper to cause a strong bond between the component metals and then cooling the composite slab.

point out and distinctly 3. A method of making a composite metal slab which consists in contacting the slab with a buming flux of the alkyl-borate type to deposit a thin layer of boric oxide on the surface thereof, heating said flux coated metal slab to a temperature of from about 800 F. to about 1500 F., pouring a metal different from said first metal onto the flux coated surface of the first layer of metal, heating both metals to a temperature above the melting point of the poured metal to cause a strong bond between the component metals and then cooling the composite slab.

4. A method of making a composite metal slab which consists in contacting a layer of metalwith a burning flux of the alkyl-borate type to deposit a thin layer of boric oxide on the surface thereof, heating said flux-coated metal to a temperature of from about 800 F. to about 1500 F., pouring a metal different from said first metal onto the flux-coated surface of said first-metal, said applied metal being at a temperature of from about 1900 F. to about 2500 F., then heating both metals for not less than two minutes to a temperature above the melting point of the applied metal to form a strong bond between the component metals. and then cooling the composite slab.

5. A method of making a composite metal slab which consists in contacting a layer of steel with a burning flux of the alkyl-borate type to deposit a thin layer of boric oxide on the surface thereof, heating the steel to a temperature of from about 800 F. to about 1500 F., pouring molten copper at a temperature of from about 1900 F. to about 2500 F. onto the flux-coated surface of the steel, then heating both metals for not less than two minutes to a temperature above the melting point of copper to form a strong bond between the copper and steel, and then cooling the slab.

6. A method of making a composite metal slab which comprises the steps of contacting the slab with a burmng flux of the alkyl-borate type to deposit a thin layer of boric oxide on substantially the entire surface of the slab, then heating the entire flux-coated metal slab to a temperature in excess of 800 F., and then casting a molten metal different from said first metal onto substantially the entire flux coated surface of said heated slab.

7. A method of making a composite metal slab which comprises the steps of pouring a liquid flux of the alkylborate type onto a slab of metal, then igniting said flux to leave a thin residue of boric oxide on the'surface of said slab, and then applying a molten metal different from said first metal onto the flux coated surface of said slab.

8. A method of making a composite metal slab which comprises the steps of pouring a liquid flux of the alkyl-borate type onto a slab of metal, then igniting said flux to leave a thin residue of boric oxide on the surface of said slab, preheating said slab to a temperature in excess of 800 F., and then applying a molten metal different from said first metal onto the flux coated surface of said heated slab.

CHARLES A. 

